Complete implementation

1 files changed, 85 insertions, 0 deletions

diff --git a/scene-loader.scm b/scene-loader.scm
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+(module downstroke/scene-loader *
+  (import scheme
+          (chicken base)
+          (only srfi-1 filter-map)
+          (srfi 69)
+          (prefix sdl2 "sdl2:")
+          (prefix sdl2-ttf "ttf:")
+          defstruct
+          downstroke/tilemap
+          downstroke/world
+          downstroke/engine)
+
+  ;; Create a prefab registry from alternating symbol/constructor pairs.
+  ;; Returns a srfi-69 hash-table mapping symbols to constructor functions.
+  (define (make-prefab-registry . pairs)
+    (let ((ht (make-hash-table)))
+      (let loop ((p pairs))
+        (if (null? p) ht
+            (begin
+              (hash-table-set! ht (car p) (cadr p))
+              (loop (cddr p)))))))
+
+  ;; Instantiate a prefab by type from the registry.
+  ;; Returns the entity plist if type exists, #f otherwise.
+  (define (instantiate-prefab registry type x y w h)
+    (let ((ctor (hash-table-ref/default registry type #f)))
+      (and ctor (ctor x y w h))))
+
+  ;; Convert TMX object list to entities.
+  ;; Object types are strings from XML; convert to symbols before instantiating.
+  ;; Filters out #f results (objects without registered prefabs).
+  (define (tilemap-objects->entities tilemap instantiate-fn)
+    (filter-map
+      (lambda (obj)
+        (instantiate-fn (string->symbol (object-type obj))
+                        (object-x obj) (object-y obj)
+                        (object-width obj) (object-height obj)))
+      (tilemap-objects tilemap)))
+
+  ;; Create an SDL2 texture from the tileset image embedded in a tilemap.
+  (define (create-tileset-texture renderer tilemap)
+    (sdl2:create-texture-from-surface
+      renderer
+      (tileset-image (tilemap-tileset tilemap))))
+
+  ;; Load a TMX tilemap file and store it in the game asset registry.
+  ;; Returns the loaded tilemap struct.
+  (define (game-load-tilemap! game key filename)
+    (let ((tm (load-tilemap filename)))
+      (game-asset-set! game key tm)
+      tm))
+
+  ;; Load a TSX tileset file and store it in the game asset registry.
+  ;; Returns the loaded tileset struct.
+  (define (game-load-tileset! game key filename)
+    (let ((ts (load-tileset filename)))
+      (game-asset-set! game key ts)
+      ts))
+
+  ;; Load a TTF font file and store it in the game asset registry.
+  ;; size is the point size. Returns the loaded font.
+  (define (game-load-font! game key filename size)
+    (let ((font (ttf:open-font filename size)))
+      (game-asset-set! game key font)
+      font))
+
+  ;; Load a scene from a TMX tilemap file.
+  ;; 1. Loads the tilemap from the file (and stores in assets)
+  ;; 2. Creates a texture from the tilemap's tileset image
+  ;; 3. Creates a scene with empty entities list
+  ;; 4. Sets the scene on the game
+  ;; Returns the scene.
+  (define (game-load-scene! game filename)
+    (let* ((tm    (game-load-tilemap! game 'tilemap filename))
+           (tex   (create-tileset-texture (game-renderer game) tm))
+           (scene (make-scene
+                    entities:        '()
+                    tilemap:         tm
+                    camera:          (make-camera x: 0 y: 0)
+                    tileset-texture: tex
+                    camera-target:   #f)))
+      (game-scene-set! game scene)
+      scene))
+
+) ;; end module